Add tests for FigureCanvasBase.get_default_filename()

Author: Umair Idris

lib/matplotlib/tests/test_backend_bases.py

@@ -1,8 +1,16 @@
+from matplotlib.backend_bases import FigureCanvasBase
 from matplotlib.backend_bases import RendererBase
+from matplotlib.testing.decorators import image_comparison, cleanup
+
+import matplotlib.pyplot as plt
 import matplotlib.transforms as transforms
 import matplotlib.path as path
-import numpy as np
 
+from nose.tools import assert_equal
+
+import numpy as np
+import tempfile
+import os
 
 def test_uses_per_path():
     id = transforms.Affine2D()
@@ -43,3 +51,30 @@ def check(master_transform, paths, all_transforms,
     check(id, paths, tforms, offsets, facecolors, [])
     check(id, paths, tforms, offsets, [], [])
     check(id, paths, tforms, offsets, facecolors[0:1], edgecolors)
+
+@cleanup
+def test_get_default_filename():
+    test_dir = tempfile.mkdtemp()
+    plt.rcParams['savefig.directory'] = test_dir
+    fig = plt.figure()
+    canvas = FigureCanvasBase(fig)
+    filename = canvas.get_default_filename()
+    assert_equal(filename, 'image.png')
+
+@cleanup
+def test_get_default_filename_already_existing():
+    # From #3068: Suggest non-existing default filename
+    test_dir = tempfile.mkdtemp()
+    plt.rcParams['savefig.directory'] = test_dir
+    fig = plt.figure()
+    canvas = FigureCanvasBase(fig)
+
+    # create 'image.png' in figure's save dir
+    with open(os.path.join(test_dir, 'image.png'), 'a'):
+        filename = canvas.get_default_filename()
+        assert_equal(filename, 'image-1.png')
+
+
+if __name__ == "__main__":
+    import nose
+    nose.runmodule(argv=['-s', '--with-doctest'], exit=False)